This proposal describes the establishment of a National Resource for Aplysia, whose overall goal is to provide consistently high quality cultured sea hares aplysia californica (and their cultured red algae food Gracilaria sp.) To NIH sponsored researchers. A. Californica is an important non- vertebrate (opisthobranch mollusc) model system for health related research, in the neurophysiology of behavior and learning. We will produce animals for research, and will conduct basic research aimed at exploring new model uses and at improving the resource. There are four sub-project/specific aims. 1. Production- We will increase our projected 1994 production by approximately 225% over the tenure of this grant and will make specimens from all life stages available at a price competitive with field-collected specimens. 2. Genetics- We will perform population genetic studies to characterize the amount of genetic variation present in our hatchery population in comparison to natural populations. The use of this genetic information will be to provide NIH-sponsored investigators with heterozygosity data for the hatchery population and with genetic markers for desirable/undesirable traits. 3. Developmental Neurophysiology-This project will investigate the regulation of neuronal excitability affecting reproductive development. The single cell voltage clamp technique will be applied to the study of the development of the capability of modulatory stimuli to act on ionic currents in applied to the study of the development of the capability of modulatory stimuli to act on ionic currents in neurosecretory bag cells. Development of this modulatory capability is an integral part of sexual maturation. This sub-project will further characterize the neurophysiology of immature A. Californica, potentially leading to a new model use, and will yield information useful to hatchery maturation and breeding strategies. 4. Animal Health Monitoring-We will establish a monitoring program based on screening of water quality and animal health parameters to assure rapid detection and complete documentation of any disease processes that might occur in any developmental stages of animal at the hatchery. Any disease syndromes and suspected pathogens observed will be investigated and appropriate control measures applied.